However, in judging a fetus "one of us," and granting it the moral and legal rights of a human being, I put the age much later, at twenty-three weeks, when life is sustainable and that fetus could, with a little help from a neonatal unit, survive and develop into a thinking human being with a normal brain. This is the same age at which the Supreme Court has ruled that the fetus becomes protected from abortion.
As a father, I have a perceptual reaction to the Carnegie developmental stages of a fetus: the image of Stage 23, when the fetus is approximately eight weeks old, suggests a small human being. Until that stage, it is difficult to tell the difference between a pig embryo and a human embryo. But then-bingo-up pops the beginning shape of the human head, and it looks unmistakably like one of us. Again, this is around eight weeks, more than two thirds into the first trimester. I am reacting to a sentiment that wells up in me, a perceptual moment that is stark, defining, and real. And yet, at the level of neuroscientific knowledge, it could easily be argued that my view is nonsensical. The brain at Carnegie Stage 23, which has slowly been developing from roughly the fifteenth day, is hardly a brain that could sustain any serious mental life. If a grown adult had suffered massive brain damage, reducing the brain to this level of development, the patient would be considered brain dead and a candidate for organ donation. Society has defined the point at which an inadequately functioning brain no longer deserves moral status. If we look at the requirements for brain death, and examine how they compare with the developmental sequence, we see that the brain of a third-trimester baby, or perhaps even a second-trimester baby, could be so analyzed. So why would I draw a line at Carnegie Stage 23 when the neuroscientific knowledge makes it clear that the brain at this stage is not ready for prime-time life?
I am trying to make a neuroethical argument here, and I cannot avoid a "gut reaction." Of course, it is my gut reaction, and others may not have it at all. In recognizing it within me, however, I am able to appreciate how difficult these decisions are for many people. Even though I can't imagine, and do not have, a gut reaction to seeing a fourteen-day-old blastocyst, an entity the size of the dot of an i on this page, that dot may serve as a stimulus to the belief system of those who hold that all fertilized eggs are worthy of our respect. Still, I would argue that assigning equivalent moral status to a fourteen-day-old ball of cells and to a premature baby is conceptually forced. Holding them to be the same is a sheer act of personal belief.
The Continuity and Potentiality Arguments
Obviously there is a point of view that life begins at conception. The continuity argument is that a fertilized egg will go on to become a person and therefore deserves the rights of an individual, because it is unquestionably where a particular individual's life begins. If one is not willing to parse the subsequent events of development, then this becomes one of those arguments you can't argue with. Either you believe it or you don't. While those who argue this point try to suggest that anyone who values the sanctity of human life must see things this way, the fact is that this just isn't so. This view comes, to a large extent, from the Catholic Church, the American religious right, and even many atheists and agnostics. On the other side, Jews, Muslims, Hindus, many Christians, and other atheists and agnostics do not believe it. Certain Jews and Muslims believe that the embryo deserves to be assigned the moral status of a "human" after forty days of development. Many Catholics believe the same, and many have written to me expressing those views based on their own reading of church history.
When we examine the issue of brain death, that is when life ends, it also begins to become clear that something else is at work here: our own brain's need to form beliefs. If we examine how a common set of accepted rational, scientific facts can lead to different moral judgments, we see the need to consider what influences these varying conclusions, and we can begin to extricate certain neuroethical issues from the arbitrary contexts in which they may initially have been considered.
